Fuse



May 13, 1947.

H. J. NICHOLS y FUSE Filed NOV. 14, 1939 2 Sheets-Sheet l May 13, 1947. v HJ. NICHOLS Patented May 13, 1947 ZAZtgtli 14 Claims.

to point detonating lres are equally applicable for other uses.

Detonating fuses for small antiaircraft proikectiles present particular' difiiculties because ci small and the great accelerating and `y forces to which the parts are subject in firing and in iight. It is essential that fuses for this purpose ce extremely sensitive on impact yet at the same time be entirely safe in handling Because of the great force ci seb-back on ring, the detonator may be fired by concussion while the projectile is in the bore of the gun. This makes a bore-safe featnre highly desirable. A fuse to be bore-safe ifi-lust have ad idate provisions against arming in the bore ci the gun, and in the event the detenator is exploded by concussion due to the ring of the gun, the explosion must be so limited as not to disrupt the fuse nor to cause eX- plosion or break-up ci the projectile.

A further desirable feature is that the fuse be not completely armed until the projectile has travelled some distance beyond the muzzle of the gun, since a relatively strong retarding force acts n the projectile when it strikes the air on emersing from the gun, and if the sensitive iiring elements can coact at that instant, premature detonation may result. This feature is usually termed a muzzle-safe feature. To ensure adequate sensitivity and quickness on impact with iight targets, such as winor covering of aircraft, the impact element must be of light weight, and the design should be such that the impact element strikes the target, as this elel:nent is thereby retarded, the projectile drives the detonator int-o the liring pin, producing instantaneous detonation before the projectile has been sensibly retarded. rIinis is termed supersensitive and super-quick action.

Finally, from the practical standpoint, fuses of this class should be simple in construction, easily loaded and assembled, and adapted to low cost manufacture in large quantity.

lt is therefore one of the principal objects oi' this invention to meet in a highly efiicient, reliable, and practical manner the general and special requirements above stated.

Another object is to provide simple and reliable arming means which utilize forces generated by the iiring process.

Another object is to provide a novel and effeci-.ive bore-safe feature.

Another object is to provide alternative means for extending the impact nring element after the projectile is in ilight.

Another object is to provide means by which the distance at which the fuse becomes completely armed after the projectile has left the gun may be predetermined.

Another object is to provide a novel detonator arming means utilizing the retardation of the spin of the fuse in flieht to arm the detonator, and centrifugal force to maintain the detonator in armed positioned.

Other objects will be in part obvious from the annexed drawings and in part hereinafter indicated in connection therewith by the following analysis of this invention.

This invention accordingly consists in the features of construction, combination of parts, and in the unique relation of the members and in the relative proportioning and disposition thereof, all as more completely outlined herein.

To enable others skilled in the art fully to comprehend the underlying features of this invention, that they may embody the same by the numerous modiiications in structure and relation contemplated by the invention, drawings depicting two embodiments of the invention form a part of this disclosure, and in suon drawings like characters of reference denote corresponding parts through the several views, in whichl snows greatly enlarged and in longitudinal cross section a point-impact, detonating fuse illustrating one embodiment of the invention, the mechanism being shown in unarmed condition.

Figs. la, lo and lc are transverse sections of the fuse shown in Fig. l, the sections being taken on the lines irl-ia, lb-lb, Erz-ic, as indicated in Fig. l.

Fig. 2 shows a bottom view of the fuse shown in Fig. 1.

Fig. 3 shows the same fuse as that in Fig. l, in similar section, the mechanism being in armed condition.

Fig. 3c, shows in transverse section on the line Eri-3a the fuse shown in Fig. 3 illustrating the position of the rotor in armed condition.

Fig. 4 shows in fragmentary, longitudinal section an alternative embodiment of the invention with respect to the means for extending the firing pin or striker.

Fig. 5 is a similar view, showing the iiring pin or striker extended.

Referring now to these drawings and particularly to Fig. l, the main structural element of the fuse is the :body I0, of rugged proportions, with external screw threads II at the base end dering the detonator harmless when exploded in the unarmed, hence safe, position.

Referring again to Fig. 1, the nose piece I6 houses the striker 2'I and the firing pin extender for assembly to the projectile (not shown). At mechanism. In this embodiment, the striker 2'I, the base is a cylindrical cavity, called the booster of steel and of the general form of an upholstery cavity, adapted to receive the booster cup I2, nail, is drilled axially at from the head along the latter being lled with compressed tetryl or most of its length, and cross-Wise at the inner end the like. The booster cup is held securely in 3l of the axial hole, to provide an air vent cornplace by a spun-cover lip I3 formed from the 10 municating from the point 32 of the assembled fuse body, as shown, or otherwise as desired. The fuse to the cavity in a piston cup 33 in the nose forward portion of the body is provided with an piece. When in position in the nose piece, a internally threaded cylindrical cavity adapted to small, tight-fitting split sleeve 34 is forced along receive the threaded portion I5 of a nose piece the shank 21 of the striker until the latter is I6. Rearwardly of the threaded cavity is a cyln- 15 secured rmly in place as shown. The split sleeve drical, smooth cavity I'I, called the rotor cavity, 34 is designed in such manner that its effective adapted to receive a rotor I8. Extending from weight at set-back (usually exceeding 20,000 the rotor cavity I1 to the booster cavity is a small times its normal weight) will overcome the fricdiameter axial hole 2B, counter-bored at the uptional force holding it to the striker, and cause per end to receive a small metal cup'2 I, called 20 it to slip back until stopped by the piston cup 33, the cord protector cup. The interior of the cup which latter is also a tight fit on the firing pin and the axial hole are filled with tightly comshank 21. The piston cup 33, of light strong pressed tetryl or the like, this part of the detometal and preferably of conical shape as shown, nating train being termed the detonating cord has the large diameter of such size as to fit but 22 for exploding the booster. The purpose of the 25 to slide easily in, the bore I4 of the nose piece. protector cup 2I is to protect the end of the cord Between the nose-piece and the fuse body is asvfrom moisture, and from hot gases likely to be sembled a thin but strong metal washer 35, termed generated in the event of premature explosion of the support disc, having an axial hole 36 of such the detonator. size as to fit closely the taper point 2B of the The rotor I8 mounted in the rotor cavity I'I is 30 striker. Figs. 1a. and 1b show the transverse secof short cylindrical form and considerably smaller tions of the parts described at the planes indi in diameter than the rotor cavity, and lies at cated inFig. 1. and eccentrically in the rotor cavity. The rotor Referring now to Figs. 1 and 3, the operation has an off-center round hole to receive a cylinof the fuse is as follows: On firing, due to the `drical detonator capsu1e23 located so that in one 35 set-back force, the set-back sleeve 34 slips down (the armed) position of the rotor I8 this hole along the firing pin shank 21 until stopped by becomes concentric with the axis of the fuse body the piston cup 33. The ring point 26, supported (Fig. 3a). The detonator 23 is preferably a thin, by its head 3l, remains in the hole 25 in the rotor drawn copper shell in which a highly compressed I8, preventing the rotor from rotating relative fulminate detonating charge is loaded by any 40 to its own axis. When the projectile emerges suitable loading apparatus. The assembly of the from the muzzle of the gun, the point strikes the detonator 23 is completed by covering the fulmiexterior air-bank and air under pressure due nate charge, loaded not quite to the top, by a thin to the velocity of the projectile enters the vents disc 24 cemented in place by a water-proof ce- 32, 30 and 3| in the ring pin and thence to the ment. When the detonator capsule is assembled space inside the piston cup 33, which is virtually in the rotor I8, the capsule is preferably coated air tight. This air pressure causes the firing pin with astrong, adherent cement to hold it securely 2l to be extended as shown in Fig. 3, notwithin place. standing the air pressure on the head of the firing The rotor I8 is also provided with a second pin, because the effective area 0f the piston cup Small Off-center 1101e25 adapted to receive the 50 33 is greater than the transverse area of the head ring point 25 of an impact element or iiring 3?, giving a differential DIBSSUI@ OlltWard. In pin or striker 2l, the hole being located so that fact, even if the pStOH Cup area were n0 greater when the rotor is assembled in unarmed position, than that of the head, some differential pressure the hole 25 can be rotated to lie at the axis of the Would probably eXiSIG due t0 the curvature of the fuse, Figs, 1 and 1c, The rotor preferably has 55 head, but in the interest of certain action, it is a small flat cut 28 across the periphery of the deemed preferable to have the cross area of the cylindrical portion at right angles to the diameter piston greater than that of the head. connecting the detonator hole 23 and the firing Consider now the action of the rotor I8. When pin hole 25. By referring to Figs. 1 and 1c it is the PlOjectile is in the bore of the gun, the Setseen that the construction described enables the back force on the rotor will exceed the torque firing peint 26 when assemmed in unarmed posiforce due to the angular acceleration of the protion 130 Serve as a, pivot around which the rotor jectile, hence the rotor will remain pressed against IB can freely revolve, but at the same time the the base 0f the I'OGI' Cavity and Will take up firing point 25 restrains the rotor from moving the rotation of the projectile without slipping. into any such position that the detonator 23 win 65 Snould the detonator, be exploded by the Setcome into alignment with the detonating cord 22. back frce. the exploslv gases Wm be.vented into sucent space is provided transversely between the voids hin the fuse without disrupting the fuse the detonator hole and the detonating cord that or eXp 10d-mg the booster harge I2' Should the acceleration of the proJectile be reversed in direcm event of premature exploslon of the detonator tion due to coppering or other b t t' th 2s, the detonatmg cord 2z win not be exploded. gun ,me the rotor would tend cosbufhlrn mf e In this connection, it is to be noted that the least Ward- I the Striker were projected foywgg gg: alla? of the rotor 15.011 the detfnatf' 51de, and fore it could clear the rotor hole the rotor would a. considerable Void space exists 1n the vrotor l be pressed against the front of the rotor cavity, cavity I'I. These factors contribute toward ren- 75 holding the rotor in unarmed position in a Inanner reverse to that at set-back. Hence it is evident that the ring point 26 cannot strike the detonator while in the bore of the gun.

As the projectile leaves the muzzle of the gun and the striker 2l is extended as before described, the rotor l 3 is set free and due to the retardation of the spin of the projectile in flight will start rolling around in the rim or the rotor cavity ll. However, each time the rotor rolls over, the tendency to roll is curbed due to the centrifugal component and at some distance from the muzzle of the gun, the rotor will eventually stop in stable equilibrium as illustrated in Fig. 3a., in which position the detonator 23 is in alignment with the cord 22. It is to be noted that the force due to the retardation of the spin is minor compared to centrifugal force. Th'us it is evident that the fuse is bore-safe and muzzle-safe.

The fuse being completely armed, on striking the target, even though the target be a flimsy one such as Wing fabric of an airplane, the head 3T of the striker will encounter substantial resistance and will be checked in flight. The projectile will then drive the detonator 23 into the iiring point 26, instantly detonating the former. The wave of detonation will travel with great velocity from the detonator through the detonating cord and booster charge to the projectile burster charge, exploding same. It has been shown that under the conditions here described, the detonation proceeds so rapidly that a projectile having a high explosive burster charge is fragmented within a few inches of encountering the target.

Referring now to Figs. 4 and 5, which sh'ow another embodiment of the invention with respect to the means for extending the striker, the main parts of the fuse so far as shown are as previously described except that the striker iii is not drilled, the support disc i is provided with an extruded and pierced central projection :12, and a striker extender spring i3 is added. The latter, a helical compression spring, is assembled inside the piston cup 33 around but clear of the striker shank di? and is supported and centered at the lower end by the projection e2 of the support disc iL The extender spring i3 is designed in such manner as to exert, when assembled, a force sunlcient to extend the striker 1li against the head air-pressure in flight. By proper design of the spring in relation to the air pressure on the head of the firing pin, the approximate velocity or range at which the fuse is to arm can be predetermined, if desired. Thus, for example, assume that the projectile is fired with a muzzle velocity of 3000 i. s. and it is desired to delay arming until the velocity has decreased to approximately 200i) f. s. or at a range corresponding thereto. Application of known ballistic data and formulae enables the air pressure on the striker head @d at the lower velocity to be calculated, and by designing the extender spring force to equal this pressure, arming at the approximate velocity or equivalent range can be predetermined as desired. Otherwise, the spring force is designed to exceed the pressure on the striker h'ead lli at the muzzle velocity, and the striker iii is extended and the rotor freed for arming as before described. Owing to the action of the rotor, however, complete arming is delayed until the projectile has travelled some distance from the gun.

It will be evident from the foregoing that the invention provides novel andadvantageous features in arming means for fuses, and adequately meets the general and special requirements for fuses of this class.

Without further analysis th'e foregoing will so fully reveal the gist of this invention that others can, by applying current knowledge, readily adapt it for various applications without omitting certain features that, from the standpoint of the prior art, fairly constitute essential characteristics of the generic or specific aspects of the invention, and therefore such adaptations should and are intended to be comprehended within the meaning and range of equivalency of the iollowing claims.

I claim:

l. In a fuse of the class described, in combination, a fuse body formed with an axially concentric cylindrical rotor cavity and carrying a booster charge at the rear end and a detonating train communicating therewith, a cylindrical rotor pivotally in said cavity in such manner as to be free to revolve in a plane transverse to the axis of the fuse body and carrying a detonator adapted to produce detonation of said train and thence of said charge, a nose piece secured to said fuse body formed with an axial bore, an impact striker and arming means therefor mounted in said bore, said striker in the unarmed position acting as a pivot for said detonator rotor permitting said rotor to revolve thereabout, but restraining said rotor from rotating into such position as to make said detonator effective to produce detonation of the booster charge.

2. In a fuse of the class described, in combination, a fuse body with an axially concentric cylindrical rotor cavity, an impact firing pin having an impact head and a shank slidably mounted in the nose of the fuse, means frictionally mounted on said shank for holding the firing pin normally in unarmed position, means coacting with said holding means after iiring in a gun to move the iiring pin forwardly into armed position, a cylindrical rotor mounted in said cavity, said rotor carrying a detonator and being normally pivoted on said firing pin to maintain the detonator in sate position, said rotor being characterized by being so formed and proportioned that aiter firing in a gun and after the ring pin is armed, it will roll in said cavity to a stable position to arm the detonator.

3. A fuse of the class described including the combination of a fuse body with a central concentric rotor cavity and safety mechanism therein including an impact ring pin, safety means frictionally mounted thereon for holding the nring pin normally in unarmed position in body and on setback to release said firing pin preparatory to arming, kinetic means operatively associated with said iiring pin and effective after the fuse is red in a gun to advance the firing pin into armed position, a cylindrical roto-r revolvably mounted in said cavity and normally restrained by said firing pin, but free to revolve thereabout, a detonator mounted eccentrically in said rotor. the combination being adapted to prevent the detonator from moving from safe position before or during firing in a gun, but to revolve the detonator into armed position a short interval after firing.

4. A fuse of the class described, including a body formed with a central concentric cylindrical rotor cavity and containing a bore-safe and muzzle-safe firing device comprising a headstriker iiring pin, set-back actuated means frictionally mounted thereon normally holding said firing pin in unarmed position and on firing adapted to release said firing pin, a cylindrical rotor carrying an eccentrically mounted detonator and normally pivoted freely on said firing pin, arming means coasting with said setback means and effective after firing in a gun to extend said firing pin to armed position and simultaneously to release said rotor, and means residing in the form and proportions of the rotor and the rotor cavity to enable said rotor at an interval after -ring in a gun to revolve said detonator from the safe to the armed position.

5. A. fuse of the class described, including a fuse body having a cylindrical rotor cavity centrally located with its axis concentric with the fuse axis, a cylindrical rotor of materially less diameter than said cavity adapted to roll therein, a firing pin pivotally mounting said rotor and normally holding said rotor eccentrically in said cavity, a detonator mounted eccentrically in said rotor, said iiring pin acting successively as pivot means for said rotor and as ring means for said detonator after ring of the projectile, and means for arming said iiring pin.

6. A fuse as set forth in claim 5, including means inherent in the form and proportions of the detonator rotor for rolling the rotor to carry the detonator into alignment with the axis of the fuse body after the fuse has been red in a gun and the arming means has acted.

7. A fuse of the class described including a fuse 'body formed with an axially concentric cylindrical rotor cavity, animpact striker assembled axially in said body, means for advancing said striker to armed position on ring, cylindrical rotor means carrying a detonator normally mounted eccentrically in said Cavity and so formed and proportioned as to roll in said cavity thereby to carry said detonator into armed position in concentric relation to said cavity after ring, and means including said striker for restraining said rotor from rolling said detonator into armed position until after the fuse has been fired in a gun.

8. In a fuse as set forth in claim 7, including, in combination, a head-striker ring pin, frictional means adapted normally to hold said firing pin in unarmed position and on set-back to free said iiring pin for arming, and arming means eiective after firing for extending said iiring pin to armed position.

9. In a fuse, a body structure having a central concentric rotor cavity and a cylindrical rotor eccentrically mounted therein carrying a detonator, said rotor being characterized by inherent means due to form and balance for utilizing the retardation of the spin of the fuse in flight to revolve the detonator from safe to armed position.

10. A rotor element as set forth in claim 9, including the said inherent means due to form and balance for utilizing centrifugal force to maintain said detonator in stable position after rotation into armed position.

11. A sensitive impact fuse for rotative projectiles, including a body part having an axially concentric cylindrical rotor cavity in the approximate center of said body part, a nose part with an axial bore assembled to said body part, firing mechanism assembled in said axial bore including an impact striker having a head, a shank, and a ring point, safety means frictionally mounted on the shank of said striker, kinetic means assembled in said axial bore for arming said striker, and a cylindrical rotor with a detonator mounted eccentrically therein and eccentrically positioned in said rotor cavity, said rotor being normally freely pivoted on said firing point.

12. In a fuse as set forth in claim 11 in which the striker is moved forwardly after ring to release the rotor to permit it to move in the cavity to carry the detonator into armed position.

13. A point detonating impact fuse comprising a body structure formed with an axially concentric cylindrical rotor cavity and carrying a booster charge at the rear end thereof, an impact striker having a firing pin and axially slidable in said body structure, safety means mounted on said striker, means for moving said striker to armed position, a cylindrical self-actuated safety rotor carrying a detonator and pivotally mounted on said firing pin in eccentric relation to said rotor cavity so that the detonator is safe from action by the ring pin and is harmless in the event of premature explosion of said detonator, said rotor being so mounted on the said ring pin as to be released from pivotal action upon movement of the striker to armed position and so formed and proportioned that after the fuse has been red in a gun and the striker has moved to armed position the rotor Will roll in said rotor cavity into armed position whereby the detonator is presented to the action of the ring pin and becomes effective to detonate said booster charge.

14. A fuse as set forth in claim 7 wherein said last named means acts as a pivot for said rotor.

HARRY J. NICHOLS.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,870,405 Doe Aug. 9, 1932 1,561,687 Brayton Nov. 17, 1925 1,342,652 Sullivan et al June 8, 1920 1,352,543 Schneider Sept. 14, 1920 2,030,085 Woodberry Feb. 11, 1936 1,774,043 Summerbell Aug. 26, 1930 FOREIGN PATENTS Number Country Date 127,924 Great Britain June 19, 1919 145,829 Great Britain June 28, 1920 505,055 France Apr 23, 1920 760,486 France Dec. 14, 1933 

